Just my two cents. Both Grant and Lee were military men leading soldiers in a war. At that time in history, the way war was fought with the technology of the times, casualties were extremely heavy and expected to be. In contrast, Joseph E Johnston who sought to avoid heavy casualties by retreating was demonized for hs philosophy of warfare.

The real butchers of history were the ones who, in addition to the massive losses of their own military and their enemies, were the ones who also ruthlessly slaughtered thousands upon thousands of civilians including women and children.

Neither Grant nor Lee ever came anywhere near such levels of atrocities as were perpetrated in ancient times or even as recently as World War Two or even under the Pol Pot regime on Cambodia.